1. Field of the Invention
The present invention generally relates to the field of radio frequency identification (RFID). More particularly, the present invention relates to RFID devices and readers.
2. Description of the Related Art
Goods and other items may be tracked and identified using a radio frequency identification (RFID) system. A conventional RFID system 100 is illustrated in FIG. 1. RFID system 100 includes at least one tag 106, which is typically placed on an item 112 to be tracked. RFID tag 106 is a small transponder that can be read by an RFID reader 102 (also referred to as an RFID interrogator). Reader 102 includes a transceiver and an antenna 104. The antenna 104 emits electromagnetic (EM) waves generated by the transceiver, which, when received by tag 106, activate the tag 106. Once tag 106 has been activated, it communicates using radio waves back to reader 102, thereby identifying item 112 to which tag 106 is attached.
There are three basic types of RFID tags. A beam-powered tag is a passive device which receives energy required for operation from the EM waves generated by the reader. The beam powered tag rectifies an EM field and creates a change in reflectivity of the field which is reflected to and read by the reader. This is commonly referred to as continuous wave backscattering. A battery-powered semi-passive tag also receives and reflects EM waves from the reader. However, the battery powered tag includes a battery to power the tag independent of receiving power from the reader. An active tag actively transmits EM waves which are then received by the reader.
Applications of RFID systems typically involve inexpensive and disposable tags. Thus, high volume manufacturing methods and systems are used to produce conventional tags. Antennas for such tags are often screen printed on tape or flexible web material. As to be expected, conventional tags are not suitable for extended use in harsh environments. For example, in a warehouse environment, exposed tags are often damaged by impacts with pallets, forklifts, and other heavy equipments, resulting in inoperability of the tag. In fact, in these environments, reader antennas are sometimes damaged as well.
From the above it is seen that techniques for durable RFID devices are desired.